Sockets for electric bulbs



Filed Sept. 10, 1963 S/L VA 4 0 f'lLfS/ A fry United States Patent 3,208,032 SOCKETS FOR ELECTRIC BULBS Silvano Tilesi, Via Palestro 6, Florence, Italy Filed Sept. 10, 1963, Ser. No. 307,996 Claims priority, application Italy, Sept. 25, 1962, 19,194/ 62 3 Claims. (Cl. 339-476) This invention concerns sockets for electric bulbs or incandescent lamps of the type comprising a spigot having contact or terminal wires extending therealong, which bulbs are usually of miniature form and are generally used for decorative purposes, for example on Christmas trees; Such sockets have a recess for receiving the spigot of the bulb and terminals for engagement by the contact wires of the bulb so as to provide for energization of the lamp.

The socket comprises a unitary molded body formed of suitable thermoplastic insulating material. A recess comprising two axially aligned cylindrical portions is formed in the body. The outer portion of the recess is open at one end of the body. The inner portion of the recess is of smaller diameter than the outer portion and is axially spaced inwardly of the outer portion. The adjacent ends of the two portions are joined by an annular shoulder portion of the body. Two diametrically opposed slots extend from the shoulder along diametrically opposed side portions of the inner portion of the recess and communicate directly with the interior of the inner portion through confronting windows. Two insulated lead wires are molded into the body. Each lead wire has a bare end portion which extends from the shoulder along the interior of one of the slots. A metal strip is disposed in each slot to engage the bare end of the lead wire and close the window of the slot.

The lamp has a collar portion which enters the outer recess with a snug fit. The spigot portion enters the inner recess and each of the terminal wires engages one of the metal plates, thereby being electrically connected to one of the lead wires.

The invention will be described further, by way of example, with reference to the accompanying drawings, in which:

FIG. 1 is a cross-sectional side elevation of the body of a socket according to the invention, the section corre sponding to the line II of FIG. 2;

FIG. 2 is a sectional elevation of the same body, corresponding to the line 11-11 of FIG. 1;

FIG. 3 is a part-sectional plan view of the body of FIGS. 1 and 2, the section corresponding to the line III-III of FIG. 1;

FIG. 4 is a section corresponding to the line IVIV of FIG. 1;

FIG. 5 is a part-sectional elevation similar to FIG. 1 but showing the complete socket;

FIG. 6 is a sectional view also of the complete socket, this view corresponding to FIG. 2; and

FIG. 7 is a section corresponding to the line VIIVII of FIG. 5.

In the drawings, a socket for a miniature electric light bulb, for example of the type employed for decorative purposes, comprises a unitary body 1 made of a material which is formable in a mould or die and which is elec- 3,208,032 Patented Sept. 21, 1965 trically insulating. For ease of manufacture, such material is preferably a thermoplastic. The body 1 is shaped to provide, at one end, an axial extension 1a, and at the other end an axial recess 2, 3 for the reception of a spigot T of a miniature electric bulb L. Such bulb L is provided with a pair of terminal wires or contacts C each comprising a bare wire connected with the filament of the bulb L and extending through the spigot T which may be integrally formed with the envelope of the bulb L or may be separately formed and arranged to support the contacts C. The wire of the contacts C is bent so that such contacts extend axially along the outside of the spigot T at two approximately diametrically opposite positions. The spigot T is formed with an enlarged portion or collar T adjacent the envelope of the bulb L.

The recess comprises a large diameter outer cylindrical portion 2 opening at the surface of the body 1 and an inner smaller diameter portion 3 connecting with the large diameter portion at a step or shoulder 4 (FIGS. 1, 2 and 5). Extending into the body 1 at two diametric'ally opposed locations and parallel to the axis of the body are two slots 3a which are open at their outer ends at the step or shoulder 4, these slots 3a communicating directly with the smaller diameter portion 3 of the recess through elongated windows can more particularly be seen from FIG. 5. It will be observed that the inner sides of the slots 3a are defined by parallel planes which secant planes with respect to the cylinder defined by the small diameter portion 3 of the recess and that the two parallel lines of intersection between each plane and the cylinder define the sides of each window. The slots 3a serve each to receive a respective metal contact strip 5 closing the window in such a manner that such contact strips are exposed along the small diameter part 3 of the recess. Thus, when the bulb L is inserted into the socket by movement in the direction of the arrow in FIG. 6, with the contact C in alignment with the openings between the small diameter part 3 of the recess and the slots 3a, the contacts C move into intimate and positive engagement with the contact strips 5. This arrangement provides for simple and convenient fitting and removal of the bulb L without the need for providing a special end cap on the bulb L.

In the production of the body 1, flexible supply leads 7 are embodied therein. In the illustrated embodiment, these leads emerge from the body 1 by way of the axial extension 1a thereof, but it will be appreciated that this is not essential and the arrangement may be such that the leads emerge at any suitable positions on the body 1. The leads 7 embody insulating sheaths or coverings and project into the large diameter part 2 of the recess in the body at the step or shoulder 4. Each of the leads 7 has a bared portion 7a from which the insulation has been stripped and such bared portions each emerge from the shoulder 4 in a position convenient for being bent so as to extend along the interior of one of the slots 3a, such positions preferably being close to the open ends of the slots 3a as shown in the drawings.

With this arrangement of the leads 7 and the bared ends 7a thereof, assembly of the components of the socket is effected by bending down the bared ends 7a of the leads and then sliding the contact strips 5 into their respective slots 3a so that such strips 5 serve to engage the respective bared ends 7a along the windows between the small diameter part 3 of the recess and the slots 3a, the strips 5 serving, as shown in FIGS. 6 and 7, to trap the respective bared ends 7a between themselves (i.e. the strips 5) and the confronting faces of the respective slots 3a. Once the contact strips 5 have been inserted into their slots 3a, they have a firm and secure contact with the respective bared ends 7a, and constitute the lamp supply terminals of the socket, without the need for any other means for providing a firm metal to metal contact of a mechanical nature between the contact strips 5 and the bared ends 7a of the leads 7.

When the bulb L is inserted into the socket, the spigot T enters the small diameter part 3 of the recess, and the collar T enters into the larger diameter part 2, the collar T serving to provide a snugly fitting moisture-tight seal with the body. Entry of moisture into the recess 2, 3, is therefore prevented, since the leads 7 are molded into the body 1 of the socket.

-In the production of the socket as described, provision is made for locating a pair of leads 7 in a die or mould of the desired shape for the body 1 and an appropriate thermoplastic material is injected into the die or mould so that the body is moulded around such leads 7. The molding of the thermoplastic material around the insulated wires causes the wires to be fixedly secured by direct engagement of the insulated wires with the molded insulating material. After removal of the body 1 from the die or mould, the leads are appropriately cut back (if necessary) and bared or stripped back to the points of emergence at the step or shoulder 4 to provide the bared ends 7a.

If so desired, for the production of series connected sockets, a single length of insulated wire is molded into the body 1 so as to form the two external leads 7 with a loop of the continuous wire extending across the wide diameter part 2. After moulding of the body 1, the loop of the wire is cut at an intermediate position and is trimmed back (if necessary) and then the resulting short leads 7a are stripped of insulation back to the step or shoulder 4 as already described.

While I have shown and described what I believe to be the best embodiments of my invention, it will be apparent to those skilled in the art that various changes and modifications may be made therein without departing from the spirit and scope of the invention as defined in the appended claims.

What I claim is:

1. A lamp socket of the class described, comprising: a unitary elongated body integrally formed of insulating material, said body having a cylindrical recess formed therein, said recess being open toward one end of said body, said recess being dimensioned to receive a hollow cylindrical spigot portion of a lamp formed integrally with the lamp envelope and which projects outwardly beyond the lamp coaxially therewith, said spigot portion having terminal wires for energizing the lamp extending axially along its outer surface at diametrically opposed lateral portions thereof, said body having two axially elongated diametrically opposed slots formed therein which extend parallel to the axis of said recess and which communicate directly with said recess along diametrically opposed portions thereof to define confronting elongated windows having spaced sides which are parallel to the axis of said recess, two insulated lead wires each comprising a portion intermediate its ends which extends from the exterior of said body to an internal position near one end of one of said slots, each of said lead wires being fixedly secured by direct engagement with said insulating material continuously throughout the entire external surface of said portion thereof which extends from said exterior of said body to said internal position, each lead wire having a bare end portion which extends from said internal position longitudinally within one of said slots, and two elongated electrically conductive strips each positioned in one of said slots between the window thereof and the bare end portion of the wire which is located therein, said strip engaging said bare end portion whereby, when said lamp is inserted in said socket, each of said terminal wires will engage one of said strips thereby becoming electrically connected to one of said lead wires.

'2. A lamp socket of the class described, comprising: a unitary elongated body integrally formed of insulating material, said body having a central recess formed therein, said recses comprising two axially aligned cylindrical portions, one portion opening at one end of said body, the other portion being axially spaced inwardly from said one portion and being of a diameter smaller than said one portion, the inner end of said one portion and the outer end of said other portion being joined by a shoulder portion of said recess, the diameter of said one portion being dimensioned to receive a collar portion of the base of a lamp and the other portion being dimensioned to receive an extending cylindrical spigot member formed integrally with the lamp envelope and which projects outwardly beyond the collar portion of the lamp coaxially therewith, said spigot member having terminal wires for energizing the lamp extending axially along its outer surface at diametrically opposed lateral portions thereof, said body having two axially elongated diametrically opposed slots of generally rectangular cross-section formed therein which extend from said shoulder portion along said other portion of said recess and which communicate directly with said other portion of said recess along diametrically opposed portions thereof to define confronting elongated windows having spaced sides which are parallel to the axis of said recess, two insulated lead wires each comprising a portion intermediate its ends which extends from the exterior of said body to said shoulder portion, each of said lead wires being fixedly secured by direct engagement with said insulating ma terial continuously throughout the entire external surface of said portion thereof which extends from said exterior of said body to said shoulder portion, each lead wire having a bare end portion which extends from said shoulder portion longitudinally within one of said slots, and two elongated electrically conductive strips each positioned in one of said slots between the window thereof and the bare end portion of the wire which is located therein, said strip engaging said bare end portion whereby, when said lamp is inserted in said socket, each of said terminal wires will engage one of said strips, thereby becoming electrically connected to one of said lead wires.

3. A lamp socket of the class described, comprising: a unitary elongated generally cylindrical body integrally formed of insulating material, said body including an integrally formed extension projecting axially from one end thereof, said body having cylindrical recesses formed therein in axial alignment with the axis of said body, one recess being open at the other end of said body, the other recess being axially spaced inwardly from said one recess and being of a diameter smaller than said one recess, the inner end of said one recess and the outer end of said other recess being joined by a shoulder portion of said body, the diameter of said one recess being dimensioned to receive a collar portion of the base of a lamp and the other recess being dimensioned to receive a hollow cylindrical spigot portion formed integrally with the lamp envelope and which projects outwardly beyond the collar portion of the lamp coaxially therewith, said spigot portion having terminal wires for energizing the lamp extending axially along its outer surface at diametrically opposed lateral portions thereof, said body having two axially elongated diametrically opposed slots formed therein which extend inwardly from said shoulder portion and which communicate directly with said other recess along diametrically opposed portions thereof to define confronting elongated windows having spaced sides which are parallel to the axis of said other recess, two insulated lead wires each comprising'a portion intermediate its ends which extends from the free end of said extension of said body to said shoulder portion thereof, each of said lead wires being fixedly secured by direct engagement with said insulating material continuously throughout the entire external surface of said portion thereof which extends from said exterior of said body to said shoulder portion, each lead wire having a bare end portion which extends from said shoulder portion longitudinally within one of said slots, and two elongated electrically conductive strips each positioned in one of said slots between the window thereof and the bare end portion of the wire which is located therein, said strip engaging said bare end portion whereby, when said lamp is inserted in said socket, each of said terminal wires will enter into electrically conductive contact with one of said strips.

References Cited by the Examiner UNITED STATES PATENTS Strickland 339'176 X Tiscione 339184 Tiscione 339-484 X Gilbert 33997 Berman 339195 X Franz 339--l76 Arena 339176 Lieberman 18-59 Brosius 339l76 X Francis 29-155.55 Capel 339-176 X JOSEPH D. SEERS, Primary Examiner. 

1. A LAMP SOCKET OF THE CLASS DESCRIBED, COMPRISING: A UNITARY ELONGATED BODY INTEGRALLY FORMED OF INSULATING MATERIAL, SAID BODY HAVING A CYLINDRICAL RECESS FORMED THEREIN, SAID RECESS BEING OPEN TOWARD ONE END OF SAID BODY, SAID RECESS BEING DIMENSIONED TO RECEIVE A HOLLOW CYLINDRICA SPIGOT PORTION OF A LAMP FORMED INTEGRALLY WITH THE LAMP ENVELOPE AND WHICH PROJECTS OUTWARDLY BEYOND THE LAMP COAXIALLY THEREWITH, SAID SPIGOT PORTION HAVING TERMINAL WIRES FOR ENERGIZING THE LAMP EXTENDING AXIALLY ALONG ITS OUTER SURFACE AT DIAMETRICALLY OPPOSED LATERAL PORTIONS THEREOF, SAID BODY HAVING TWO AXIALLY ELONGATED DIAMETRICALLY OPPOSED SLOTS FORMED THEREIN WHICH EXTEND PARALLEL TO THE AXIS OF SAID RECESS AND WHICH COMMUNICATE DIRECTLY WITH SAID RECESS ALONG DIAMETRICALLY OPPOSED PORTIONS THEREOF TO DEFINE CONFRONTING ELONGATED WINDOWS HAVING SPACED SIDES WHICH ARE PARALLEL TO THE AXIS OF SAID RECESS, TWO INSULATED LEAD WIRES EACH COMPRISING A PORTION INTERMEDIATE ITS ENDS WHICH EXTENDS FROM THE INTERIOR OF SAID BODY TO AN INTERNAL POSITION NEAR ONE END OF ONE OF SAID SLOTS, EACH OF SAID LEAD WIRES BEING FIXEDLY SECURED BY DIRECT ENGAGEMENT WITH SAID INSULATING MATERIAL CONTINUOUSLY THROUGHOUT THE ENTIRE EXTERNAL SURFACE OF SAID PORTION THEREOF WHICH EXTENDS FROM SAID EXTERIOR OF SAID BODY TO SAID INTERNAL POSITION, EACH LEAD WIRE HAVING A BARE END PORTION WHICH EXTENDS FROM SAID INTERNAL POSITION LONGITUDINALLY WITHIN ONE OF SAID SLOTS, AND TWO ELONGATED ELECTRICALLY CONDUCTIVE STRIPS EACH POSITIONED IN ONE OF SAID SLOTS BETWEEN THE WINDOW THEREOF AND THE BARE END PORTIN OF THE WIRE WHICH IS LOCATED THEREIN, SAID STRIP ENGAGING SAID BARE END PORTIN WHEREBY, WHEN SAID LAMP IS INSERTED IN SAID SOCKET, EACH OF SAID TERMINAL WIRES WILL ENGAGE ONE OF SAID STRIPS THEREBY BECOMING ELECTRICALLY CONNECTED TO ONE OF SAID LEAD WIRES. 